Driving power selection under the application of t

  • Detail

The choice of driving power supply under the application of LED light strip dimming

LED is more and more widely used in lighting fixtures. In addition to improving the quality of life, improving the efficiency of light sources and prolonging the service life of lamps, it uses its unique dimming function to change the color temperature and brightness of lights, and fully achieves energy-saving application as its greatest advantage

the dimming efficiency of LED lighting fixtures depends on the matched LED light source and driving power supply

generally speaking, LED light sources can be simply divided into two categories: single LED diode light source or LED diode light source with resistance. In application, sometimes led light sources will be designed as a module containing DC-DC converter, and such complex modules are not within the scope of this article. If the LED light source or module is a separate LED diode itself, the common dimming method is to adjust the amplitude of the LED input current, so the selection of the LED driving power supply should refer to this feature. The hlg/elg family of Mingwei company is characterized by adjustable current, which can be adjusted by external vdc* or 10vpwm pulse width, or even control the adjustment of the output current only through an external simple variable resistor. And the other one is equipped with resistance. Which one is low, medium, high, ultra-high frequency? The L furniture structure of the device is not strong. "Mechanical test standard" has the final say. The LED diode light source (generally known as LED light strip or ledstrip) is widely used. The LED light strip is a resistor with LED diodes in series, so the voltage is relatively stable. Therefore, users can use any constant voltage power supply on the market to drive the LED light strip. Common LED light strips are usually driven by 12VDC or 24VDC, but it may be a little difficult in the dimming application of LED light strips. This paper describes the application of current amplitude dimming driver in LED light bar, and also discusses some common dimming problems. At the same time, it introduces the dimmable LED power driver with output pulse width (PWM) modulation. The PWM family series launched by Mingwei company and recognized by the national technological innovation product award is the most appropriate and simplest LED light bar dimming scheme on the market at present

common LED dimming problems:

dimming sounds like a simple thing. In fact, many factors need to be considered to have a good and smooth dimming performance. There are many common LED dimming problems, As shown in the following table (I):

selection of LED drive power supply under LED light bar dimming application

table (I): common dimming problems

when using LED power driver with adjustable output current to dimming LED lights, deadtravel is a frequent problem. Although the LED drive power supply can operate well when it is in the full load state (as shown in Fig. 1-A), when the LED drive is not in the full load state, it is obvious that the dimming is not smooth

Figure 1: Mingwei LED driver hlg-100 is connected to the LED light bar under different load (length) conditions: (a) 100% full load -- it can produce the best dimming performance; (b) Load 70% -- shows imperfect dimming effect; (c) Load 30% - shows poor dimming results because the dimmable range is too narrow

output pulse width modulation (output PWM) solution

if the LED is used to drive the key strategic material source for LED light strip dimming application under full load, there is no problem that deadtra belongs to precision instrument vel. The above argument is true, but it is not very practical. In fact, LED light strips are often used in various applications (decorative lighting/auxiliary lighting/advertising lighting) because the length cannot be accurately estimated, so the simplest and best application solution is to correctly select the LED driving power supply with output pulse width PWM dimming function to realize the dimming demand of LED light strips. The output brightness can achieve the dimming change of reducing brightness by the load cycle of dimming signal. The important parameters for selecting the driving power supply are dimming analysis and the frequency of output pulse width modulated PWM. The minimum dimming ability should be as low as 0.1%, so as to achieve the dimming resolution of 8bit to meet all LED light bar dimming applications, and the output pulse width modulated PWM frequency should be as high as possible, In order to prevent the light flicker problem mentioned in table (I), according to the relevant technical research literature, the frequency is recommended to be at least higher than 1.25khz to reduce the ghost flicker visible to human eyes

the best LED light bar dimming scheme is to use the output pulse width modulation PWM dimming function to solve the common deadtravel dimming problems. The PWM models provided by Mingwei company cover four series, including 40/60/90/120w, which are very suitable for LED driving power supply for various LED light bar dimming applications

Copyright © 2011 JIN SHI